Teenagers will report the frequency of cigarette smoking by using a structured questionnaire. The definition of tobacco smoke exposure including: (a) ''Do you currently smoke?''-yes/no; (b) ''When did you begin to smoke regularly?''; (c) Smokers were also asked for the number of cigarettes they smoked on an average day. Nicotine dependence will be examined by using structure questionnaires from Fagerstrom model.